With so many Americans fed up with high gas prices and also obsessed with exercise, it is fueling a national boom in commuting to work by bicycle. Unfortunately, it's apparently fueling a 60% upsurge in bike shifts. Thefts. In fact, your bicycle is now four times as likely to get stolen as your car. So, police are now going high tech, and here's ABC's Neal Karlinsky. Reporter: Shameless thieves captured on camera again and again. Watch as this guy clips a lock and walks off with this bike in broad daylight. It's something San Francisco police, who have taken us out on patrol routine. So, in 2012, it was estimated, one every three hours. Reporter: One every three hours? An estimated $50 million black market in stolen bikes, sold by the same repeat offenders on craigslust or at flea markets. I've arrested almost every one here and there's a lot more, too. Reporter: Head of the bike theft unit, officer Matt Friedman, has turned catching bike thieves into a sort of sport, posting mug shots on social media like trophies and even baiting them. That bike is worth about 1,500 bucks. Reporter: It's part of a fleet of so-called bait bikes. Bikes wired with gpa trackers and left around town by police, just for thieves to steal and get caught. Officer Friedman showed us how easy it is to cut the average lock with a simple tool. So, we're going to run an experiment. This is a San Francisco police department bait bike. I'm going to cut the cable, take it. Let's see if they can find it. An app on his phone and a second receiver hone in on the bait bike. I've hit it blocks away, but it doesn't take long. You zeros right in on it. Right in on it. Reporter: He recommends small u-locks like this one. They take a lot longer to cut through. A real deterrent. But his biggest trick? To keep the crooks guessing, is it an easy target or a bait bike? Neal Karlinsky, ABC news, San Francisco.

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